The present invention relates to a diagnostic catheter used for various kinds of diagnosis by being inserted, into a body cavity or lumen such as a blood vessel, a vas, a digestive organ, etc., and particularly to a catheter used for display of a cross-sectional image of a lumen or the like purposes.
In a treatment of an anglostenosis portion possibly causing myocardial infarction or the like, an operative technique of treating the diseased part percutaneously by use of a catheter is used. The operative technique includes various methods such as a method of dilating the angiostenosis portion by a dilation catheter having a balloon at its distal end, a method of causing a metallic pipe called stent to indwell in the angiostenosis portion, a method of excising the angiostenosis portion through rotation of a grindstone or a cutter by use of an appliance called rotoblator, etc., among which a preferable method is selected according to the properties of the angiostenosis portion and the conditions of the patient.
A diagnostic catheter is mainly used as an aid to observation of the angiostenosis portion or to judgment for selection of the treating means, in the percutaneous treatment of such angiostenosis portion, and is used also for observation of the conditions after treatment.
Examples of the diagnostic catheter include an ultrasound catheter for sensing by an ultrasonic detector, and an optical tomographic imaging apparatus utilizing low-interference light.
Among these diagnostic catheters, the ultrasound catheter needs to be inserted into a complicatedly bent portion such as a coronary artery of a heart; therefore, at the time of insertion, it is a common practice to preliminarily insert a guide wire to the diseased part and then advance the ultrasound catheter along the guide wire. Accordingly, the ultrasound catheter is provided at its distal end with a lumen for inserting the guide wire therein for the purpose of moving the catheter along the guide wire (this lumen is hereinafter referred to as guide wire lumen).
The guide wire lumen is generally provided only on the distal end side, in the direction of insertion into an organism, in relation to the position of the ultrasonic detector. This is because the image pickup by the ultrasonic detector is hindered if the guide wire lumen is present in the direction in which ultrasound is generated by the ultrasonic detector.
Besides, in order to minimize the range of insertion of the catheter into an organism, it is desirable that the ultrasonic detector for picking up an image of the organism is provided as close as possible to the distal end of the ultrasound catheter. Therefore, the guide wire lumen provided on the distal end side of the ultrasonic detector must be small in axial length.
Accordingly, the ultrasound catheter has had problems as follows: the operationally of the catheter is poor, and the catheter would not move along the guide wire as desired; the guide wire would be bent, to damage a blood vessel or the like, at the time of drawing away the catheter out of the body; and the catheter would be bent at the proximal end of the guide wire lumen.
The present invention has been made in consideration of the above circumstances. Accordingly, it is an object of the present invention to provide a catheter capable of being enhanced in operationally without hindering pickup of an image.